Our last day is Saturday 11/18 which I had planned on being a MK day, we have park hoppers so I decided to make 3 early fastpasses in AK since FOP was available for that day (day 7 of the trip) and then we can hop over to MK for the rest of the day. My main goal that day is to see HEA so it doesn't really ruin anything except not being able to make fastpasses for MK ahead of time, but I'm sure we'll be able to snag a few same days. You really just have to be flexible with your days and plans and if you have hoppers be willing to use them. Have you checked any crowd calendars for that week? They're obviously not 100% accurate but they should give you a fairly good idea. I've heard that traveling early December is typically low crowd.